Fat Fingers and Other Campfire Stories
A recent well-publicized network outage prompted someone to start collecting fat-finger horror stories, and dozens of networking engineers were quick to chime in. Enjoy!
The Importance of BGP NEXT_HOP in L3VPNs
In an MPLS network with L3VPNs, it’s very easy for the NEXT_HOP attribute of a VPN route to look absolutely correct but be very wrong at the same time. In a vanilla IP network, the NEXT_HOP can point to any IP address that gets the packets moving in the right direction towards the ultimate destination. In an MPLS network, the NEXT_HOP must get the packets moving in the right direction but it must also point to the exact right address in order for traffic to successfully reach the destination.
The reason it has to be exact is because IOS only assigns MPLS labels to the next hop address and not to each individual VPN route. So when an ingress PE needs to forward a packet from a CE across the MPLS network, the PE finds the label associated with the NEXT_HOP address and uses that as the outer label to get the packet to the egress PE.
Since each NEXT_HOP has a different label, that means each NEXT_HOP is reachable through a different Label Switched Path (LSP). Different LSPs can, and likely will, forward traffic differently through the network.
An MPLS label identifies a Forwarding Equivalence Class (FEC). A FEC is Continue reading
Saving the Web, Saving Community (Heavy Topic Warning)
Is the ‘web losing it’s populist (and/or democratic) spirit? Hossein Derakhshan, at least, thinks so. he argues that the ‘web is dying because the hyperlink is dying —
Much could be made of the argument that Hossein is just feeling the effects of being disconnected for six years. After being put in prison as a political dissident six years ago, he reappears on the scene only to find out the world has moved on without him. There are several points in his article that might indicate this — that he felt like Continue reading
SD-WAN: The Killer App For Enterprise SDN?
Software-defined WAN technologies promise to help enterprises modernize their WANs by combining classic WAN technologies with SDN capabilities.White box Internet router PoC
The following traceroute run on Peer 1 shows the set of router hops from 192.168.250.1 to 192.168.251.1
[root@peer1 ~]# traceroute -s 192.168.250.1 192.168.251.1
traceroute to 192.168.251.1 (192.168.251.1), 30 hops max, 40 byte packets
1 192.168.152.2 (192.168.152.2) 3.090 ms 3.014 ms 2.927 ms
2 192.168. Continue reading
VMware Q2 Points Toward Growth Beyond vSphere
VMware forecasts a strong 2H'15.
Cloud Gains Don’t Prevent Microsoft’s Record Loss
Microsoft takes $7.4B write-down on Nokia deal.
The Importance of BGP NEXT_HOP in L3VPNs
In an MPLS network with L3VPNs, it's very easy for the NEXT_HOP attribute of a VPN route to look absolutely correct but be very wrong at the same time. In a vanilla IP network, the NEXT_HOP can point to any IP address that gets the packets moving in the right direction towards the ultimate destination. In an MPLS network, the NEXT_HOP must get the packets moving in the right direction but it must also point to the exact right address in order for traffic to successfully reach the destination.